The present invention relates to semiconductor devices and, more particularly, to a method of manufacturing a semiconductor device, in which a Drain Select Line (DSL) and a Source Select Line (SSL) can be formed to have a desired size.
Semiconductor memory devices for storing data are commonly classified into volatile memory devices and non-volatile memory devices. Data stored in volatile memory devices is lost when power is cut off, whereas data stored in non-volatile memory devices is not lost when power is cut off. Non-volatile memory devices include flash memory devices.
Flash memory has become more popular with the advent of portable devices, such as mobile phones, PDAs, cameras, game machines and MP3 players. Flash memory is becoming more commonly used as storage media for IT technologies and home appliances. Flash memory is suitable for these applications in view of its non-volatile and low-power consumption characteristics. Flash memory is also becoming more commonly used as main storage devices in various portable devices. Research has shown that flash memory may be used in an even broader range of applications. A flash memory device having a channel length of 70 nm grade or less and having a level of integration of at least 4 Gb has been recently developed.
As the line width of a semiconductor device decreases, the sizes of various patterns constituting the semiconductor device also decrease. This results in problems associated with a drawing rule of photo scanner equipment.
As can be seen in FIG. 1, a Depth Of Focus (DOF) margin varies on a pitch basis according to ArF 100 having a wavelength of 193 nm and KrF 102 having a wavelength of 248 nm. This has a great influence on the size of a gate line and space pitch.
If ArF 100 having a wavelength of 193 nm is used in a formation process of a gate, the DSL and the SSL cannot be formed at 200 nm or less in size. Consequently, it is impossible to reduce the size of the line and space pitch and, therefore, the chip size.
Accordingly, as devices continue to become smaller, the size of the line and space pitch is also reduced.